Bore finishing tool



Dec. 26, 1950 B. L. JOHNSON BORE FINISHING TOOL Filed June 24, 1948 MIVE/VTOR.

56rd l .756/750/7 Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE BORE FINISHING TOOL Berd L. Johnson, Billings, Mont.

Application June 24, 1948, Serial No. 35,030.

4: Claims,

This invention relates to a new and'improved bore finishing tool.

When an engine is having its pistons fittedwith new piston rings, it is important that; the glaze in the bores be removed so. thatthe new rings can Wear down quickly to a correct closefitthis being known as seat ng. As is well known, some rings are specially designed for quick seating? This jobpf so-called g aze busting has prompted the desig in of various finishing tools, usually inyolving the use of emery cloth or other equally e fective abras ve mediums. The majority of these, however, have not been of" a practical design, one of the principal. objections being the difficulty of replacing the, emery cloth whenworn out; Usually, too, these tools have either not been adjustable at all or the adjustments'to fit different sized bores to be finished were not of satisfactory design. Some of these tools; on the other hand, were. designed for only asingle use, which meant a rather heavy item of tool expense for such a small job. It: is, therefore; the principal object of my invention to provide a bore finishing tool of a more practical design, which facilitates replacement of" emery cloth and per mits in and out adiustmentof the springmembers carrying the emery cloth, so that one tool can be used in a number of different sizes of bores, and works-to about equal advantage in all of them.

In the tool of my invention, there are preferably four leaf springs, adjustably clamped by means ofplates fastened by bolts onto the four sides of the driven head, strips of emery cloth being placed on the outer faces ofsaid leaf springs and fastened at one end by threading in slots in the free ends of the. leaf springs and fastened at the other end by threading in slots in the clamping plates, the leaf springs being slotted in register with bolt holes in the clamping plates for the desired range of in and out adjustment to fit different diameters of bores.

The invention is disclosed in the accompanying drawing, in which Fig. 1 is a view partly in end elevation and partly in cross-section of a bore finishing tool embodying my invention, and

Fig. 2 is a side view.

The same reference numerals are applied to corresponding parts in these two views.

Referring to the drawing, the reference numeral 3 designates the elongated, hollow, foursided head designed to be driven by means of a portable electric motor operated drill chuck, into which the spindle 4 extending from the center z. of theend wall 5, provided onone end of'the head, is adapted tobe entered. The spindle 4"is fixed to the head by entry of a reduced end portion Bin a hole 'iin the end wall 5, and by welding the spindle to the end wall circumferentially of the hole on the inner and outer sides of the Wall, as indicated at 3 and 9. Two bolt holes H) are provided in each side wall of 'the head on the longitud nal center-line through which the shanks of bolts II are enteredand threaded 'into holes if in a single elongated nut I 3, whereby to fasten a clamping or hold-down plate Mnto the head and with it the flat attaching end portion lfiof'a curved leaf spring 162 Theplates l4each have two holes ll to receive the shanks of the bolts H with a close fit, whereas the attaching end portions 15 of the leaf springsit. have elongated slots l 8, the lengthofwhich determines the extent to which the leaf springs Hi. may. be

adjusted endwise inwardly or outwardly relative tothe head 3. plates l4, and bolts II. In Fig; 1, the springs is are shown adjusted inwardly as far as they will go, the inner ends l9thereof being in-abutmentwith the inner faces of'neighboring springs. course, limited by the length of the slots l8. Strips Zllof emery cloth, or other suitable abrasive material, are carried on the outer facesof leaf springs It in anysuitable way. I prefer to insert the inner end of each of these strips in a slot 2| provided therefor in the outwardly bent edge portion 22 of the associated clampingplate l4; so that the end portion 23 of thestrip overlapped by the attached end portion of the strip is gripped under the pressure with which the strip is held againsttheconvexly curbed outer face of: the

leaf spring when tightened, the other end por-- tion 24 of each strip being threaded inwardly and outwardly through closely spaced parallel slots 25 provided in the free end portion of the associated leaf spring and being pulled up tightly against the outer face of the leaf spring when threaded through the first of these slots. Passage through the second slot so close to the first slot, coupled with the friction due to the abrasive, is enough to keep the emery cloth in place, and it will also be evident that the strip is further secured as a result of having the extreme end portion 26 of the strip overlying the extreme end portion of the leaf spring, so as to be held tightly against the wall of the cylinder bore in the operation of the tool. An engine cylinder bore has been indicated in dotted lines in Fig. 1 at 21, with one of the leaf springs l6 indicated also in dotted lines as flexed to work in it, and

Outward adjustment. is, of,

the clockwise direction of rotation of the tool is indicated by the arrow 28. It will, of course, be understood that in operation all of the leaf springs I6 are flexed inwardly toward the head 3 to the extent necessary to enter the bore that is to be finished with this tool, and that I thereby insure substantially the same spring pressure on each strip of emery cloth for efiiciency in the glaze busting operation. Centrifugal force is also a factor in assuring close working contact of all of the strips of emery cloth with the wall of the cylinder.

The operation of this tool is believed to be obvious from the foregoing description. The ease with which the strips 20 of emery cloth can be removed and replaced is thought to be self-evident; also the ease of in and out adjustment of the leaf springs 56. The radius of curvature of the outer end portion 29 of each leaf spring is approximately that of the smallest bore 21 in i which the tool is adapted to be used.' When the leaf springs are adjusted outwardly to work in bores of larger diameter, there is accordingly a little less area of contact in the bore per leaf spring the farther out th springs are adjusted for larger bores. However, there is enough flexibility in the springs [6 to make them accommodate themselves somewhat to the different curvatures of the different bores, so that the efficiency of operation is not too greatly affected,

and, hence, a bore finishing tool with such adjustability is entirely practical and highly desirable,

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn to cover all legitimate modifications and adaptations.

I claim:

1. In a tool of the character described, a rotatable head providing angularly related clamping faces thereon, a leaf spring element for each face having one end portion abutting the face, a clamping plate for each face having means for fastening the same to the head to clamp the associated leaf spring element therebetween, and a flexible abrasive strip overlying th outer face of each leaf spring element and looped at one end through a slot provided in the associated clamping plate and removably fixed at the other end to the leaf spring element so that the strips may be removed and replaced without loosening the clamping plates.

2. In a tool of the character described, a rotatable head providing angularly related clamping faces thereon, a leaf spring element for each face having one slotted end portion slidably abut- 4 ting the face, the slots extending in a direction for radial adjustability of the leaf spring element relative to the axis of rotation of the head, a clamping plate for each face having means extending through the slots in the leaf spring element for fastening the same to the head adjustably to clamp the associated leaf spring element therebetween, and a flexible abrasive strip overlying the outer face of each leaf spring element and looped at one end through a slot provided in the associated clamping plate and removably fixed at the other end to the leaf spring element so that the strips may be removed and replaced Without loosening the clamping plates.

3. A honing or finishing tool for use in cylindrical bores comprising a rotatable head, flexible leaf spring elements adapted to be attached by flat inner end portions to said head and having free end portions reaching outwardly therefrom for slidable engagement in arched form circumferentially of a bore in trailing relation to the attached inner end portions, said latter end portions having elongated slots provided therein in transverse relation to the axis of rotation of said head for radial adjustability of said flexible elements relative to said head, hold-down plates overlying said slotted end portion having holes provided therein registering with said slots and receiving bolts fastening said plates and flexible elements in adjustably fixed relation to said head, each of said plates having an elongated slot provided in the edge portion thereof nearest the free end portion of the associated flexible element and substantially parallel to the axis of rotation of said head, and a sheet of flexible abrasive material overlying the outer face of each flexible element and having one end portion loop-ed through the slot in the associated holddown plate.

4. A tool as set forth in claim 3, wherein each sheet of flexible abrasive material has the outer end portion remote from the hold-down plate removably fixed to the free end portion of the flexible element so that the abrasive material may be removed and replaced without loosening the hold-down plates.

BERD L. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Num er Name Date 1,670,068 Grimes May 15, 1928 2,316 257 Krastin Apr. 13, 1943 2,4 l5,492 Pentecost July 20, 194d; 

